1. Field of the Invention
Embodiments of the present invention generally relate to a method for electrochemical processing.
2. Description of the Related Art
Electrochemical mechanical planarizing (ECMP) is a technique used to remove conductive materials from a substrate surface by electrochemical dissolution while concurrently polishing the substrate with reduced mechanical abrasion compared to conventional planarization processes. ECMP systems may generally be adapted for deposition of conductive material on the substrate by reversing the polarity of the bias. Electrochemical dissolution is performed by applying a bias between a cathode and a substrate surface to remove conductive materials from the substrate surface into a surrounding electrolyte. Typically, the bias is applied to the substrate surface by a conductive polishing material on which the substrate is processed. A mechanical component of the polishing process is performed by providing relative motion between the substrate and the conductive polishing material that enhances the removal of the conductive material from the substrate.
In many conventional systems, ECMP of the conductive film is followed by a conventional chemical mechanical processing for barrier removal. This dichotomy of processing (e.g., ECMP and CMP on a single system) requires divergent utilities and process consumables, resulting in higher cost of ownership. Moreover, as most ECMP processes utilize lower contact pressure between the substrate being processed and a processing surface, the heads utilized to retain the substrate during processing do not provide robust processing performance when utilized for convention CMP processes, which typically have high contact pressures, which results in high erosion of conductive material disposed in trenches or other features. As the removal rate of low pressure conventional CMP barrier layer processing is generally less than about 100 Å/min, conventional CMP processing of barrier materials using low pressure is not suitable for large scale commercialization. Thus, it would be advantageous for a system to be enabled to remove barrier materials, such as ruthenium, tantalum, tantalum nitride, titanium, titanium nitride and the like, through an electrochemical process.
Thus, there is a need for an improved method and apparatus for electrochemical processing of metal and barrier materials.